Heretofore, it has been well known to effect tipping and/or uprighting movements to a tooth in the Begg technique by applying horizontal force directly to the crown or uprighting force between a Begg bracket mounted on a tooth and an archwire connected to the bracket. The most common bracket employed for this technique is the type similar to the Model 256 bracket manufactured and sold by TP Laboratories, Inc. of LaPorte, Ind. This bracket includes a vertically oriented body having an occlusogingivally extending opening for receiving a lock pin, a spring pin, or other appliances, attaching flanges at the mesial and distal sides of the body and which extend somewhat above and below the upper and lower ends of the body, and a mesiodistally extending archwire slot, which when the bracket is mounted on the tooth in a given orientation is usually disposed at the gingivolingual corner of the body extending vertically and opening gingivally. Another form of this bracket differs in that the flanges are tapered and then only extend from the body below the archwire slot, but those flanges were purposely designed to never engage the archwire and therefore would be of no practical value as stops. Normally, the bracket is mounted in this manner with the archwire slot opening gingivally, but it could be mounted so that the slot opens occlusally. However, this bracket does not have any practical means for predetermining the limits of either tipping or uprighting movements which are produced by applying forces to the crown or root of a tooth to cause mesial or distal tipping of the clinical crowns or mesial or distal uprighting of the roots. Accordingly, once an appliance system has been mounted in a patient's mouth and a tipping action is commenced, such as by contact of a proximate tooth being moved or by the use of elastics or the like, the tipping action will continue until the force is expended or neutralized at a subsequent appointment, or the tooth has been placed in an undesired and possibly detrimental inclination. Unexpected over-tipping can be caused by a longer time span between appliance adjustments than planned or by the inadvertent application of excessive forces by the orthodontist or patient. When overtipping is encountered, treatment time is lengthened and/or the quality of the result can be lessened.
Uprighting of a root is usually achieved with a suitable uprighting spring appliance. Inasmuch as it is normal for expeditious uprighting that the activation of the spring would upright a tooth beyond the desired position before the spring force is expended, uprighting movement heretofore has been generally stopped by removal of the spring at a subsequent visit to the orthodontist. Such control is satisfactory if the patient returns for treatment at the next scheduled appointment, the interval between appointments is not excessive, and the tooth does not upright more rapidly than expected. Should the patient miss the next appointment or the tooth respond quickly, excessive and undesired root uprighting may take place which then must be corrected through further treatment.
Spring Pin appliances are commonly used on Begg brackets to provide uprighting movements while locking the archwire to the bracket. "Spring Pin" is a registered trademark of TP Laboratories, Inc. for an appliance that not only locks an archwire to a bracket but also produces mesial-distal uprighting movement between the bracket and the archwire. More detailed operation of the appliance may be found in U.S. Pat. No. 3,793,730, including disclosure of an arm in FIG. 2 to limit uprighting, but to date it has not proved practical to commercially provide Spring Pin appliances with this arm. Therefore, practitioners of the Begg technique sometimes run into difficulties and experience overuprighting movements, especially when the time interval between patient visits is prolonged. For example, if a patient becomes hospitalized or otherwise disposed so that the patient is unable to make the next scheduled appointment and one or more teeth are undergoing uprighting action, overuprighting movements are encountered which require rectification. Such delays can extend the orthodontic treatment and cause severe problems for both patient and orthodontist.
Excessive tipping and/or uprighting extends treatment time and delays reaching the desired end result. These problems have been considered by many orthodontists to be serious deficiencies in the Begg technique and have deterred them from using the technique.
While there have been brackets usable in the Begg technique which include wide archwire slot bases or archwire supporting bars spaced from the archwire slot, such as shown in U.S. Pat. No. 3,085,335, the purpose of these elements has been to prevent tipping. It has also been proposed by Dr. P. R. Begg to solder horizontal spurs to bands to accomplish mesial and distal bodily tooth movements and to prevent mesial and distal tipping. Dr. Angle, many years ago, proposed adding staples to bands for tying ligature wires to the archwire to effect desired inclined tooth movements.
In recent years there has been considerable development of brackets intended to produce more accurate and satisfactory orthodontic treatment. This has been particularly evident in the edgewise technique which utilizes a rectangular or square wire received in a rectangular slot. Particularly, an offshoot of the edgewise technique is the straight-wire technique which compensates for malpositioned teeth in the structure of the brackets as opposed to applying bends in the wire. However, there have not been any developments of products in the light-wire or Begg technique parallel to those in the edgewise technique for obtaining such precise and accurate tooth inclinations throughout treatment, except for attempts to combine edgewise and light wire brackets as disclosed in the Universal bracket marketed by Unitek of Monrovia, Calif.
It has been well known that the edgewise technique has relied upon closely spaced patient visits for making adjustments in the system because it is designed to produce small amounts of movement between adjustments. It has also been known that periodic patient visits when using the Begg technique are usually spaced relatively far apart because the system contemplates greater tooth movements between adjustments.
In the edgewise technique, when it is desired to move a tooth along a jaw, the tooth is bodily moved along an archwire with a heavy force, often with the help of headgear, while in the Begg technique a tooth is generally moved by first tipping the crown mesially or distally, with a relatively light force, then holding the crown against horizontal movement and uprighting the root with an uprighting spring. A further objective of each technique is to orient the tooth in a predetermined inclined position. For example, many orthodontists believe the ideal inclination of an upper cuspid measured between the vertical axis of the mouth and the long axis of the clinical crown is about 11 degrees with the root tipped toward the distal.
One of the most common objections to the Begg technique, as above mentioned, is that it is difficult to control tooth movements. More particularly, orthodontists have expressed concern that tipping and uprighting movements are difficult to control because of the lack of predetermined restriction of such movements from the bracket through its relationship with the archwire.